Abstract
Polyoma virus (PY) and pneumonia virus of mice (PVM) are not related to each other serologically (1), but because of their similarity in size and their semi-ubiquitous presence in a latent form in mice, the possibility was considered that they belong to the same or related groups of viruses. Since sensitivity to ether serves to distinguish groups of viruses (2, 3), and since it is known that PY is ether resistant (4), the reaction of PVM towards ether was investigated. Ability of the 2 viruses to grow in tissue culture, and their in vivo effects on mouse lung were also compared.
Materials and Methods. Three strains of PY were used in these experiments. Strain LID-1 (5) was kindly provided by Dr. R. J. Huebner. Strain Lp or large plaque virus was derived by Dr. R. Dulbecco by single plaque isolation from a stock originally provided by Dr. W.P. Rowe(6,7). Sp or small plaque virus was isolated from transformed hamster embryo cells after exposure to Lp virus(7). Both Lp and Sp viruses were kindly provided by Dr. R. Dulbecco. The stocks of the various strains of polyoma assayed on secondary mouse embryo layers, according to the procedure of Dulbecco and Freeman (8), contained approximately the same number of plaque forming units, about 1×108 PFU/ml.
A single stock of PVM was used. This had been prepared by Dr. F.L. Horsfall, Jr. in 1953 and had been stored at - 60 °C since that time.
Standard procedures were used for intranasal infection of mice(9) and for preparation and infection of tissue cultures. Ether treatment was done according to the procedure of Andrewes and Horstmann(2).
Lung specimens were fixed in 10% formalin and stained with hematoxylin-eosin.
Results. Results of experiments on ether sensitivity of PVM are recorded in Table 1.
Get full access to this article
View all access options for this article.